Effective Length Factor Of Semi-rigid Connected Steel Frames

This article summarizes the study on the basis of effective length coefficient of the semi-rigid connected steel frame from domestic and foreign, according to two kinds of unbalances of the beams separately which one has displacement and another has nothing, using the helical spring to simulate the node's semi-rigid, considering the different influences of node semi-rigid and the column both sides node rigidity, introducing the distribution coefficientαof the connection relative flexibility and the beam column relative corner, made up the insufficiency of the sub-structure method, obtained the formula of the beam line rigidity correction factorβ, then obtains the effective length factor revised formula of the steel frame trestle.The findings indicate: The node semi-rigid characteristic has the obvious influence on columns' effective length factor, the extent of influences has relation with the node structure, corner development as well as node rigidity ratio related. The effective length factor revised formula of the semi-rigid connected steel frame trestles which have two kinds of situation that has the displacement and has nothing is the same as steel frame trestle in《Steel structure Design Standard》, In revised formula's beam column line rigidity has considered the influence of semi-rigid and the column both sides node rigidity.Through to the project example's computation, analyzes column's effective length factor half had just met the steel frame under the horizontal load and the vertical load function, had the displacement and nothing, and separately with node for complete rigid connection and the effective length factor which calculated according to the mirror structure law has carried on the comparison, has analyzed the influence of beam column node corner development factor paired columns computation length.The findings indicated: The semi-rigid has influence on steel frame trestles which has the displacement and has nothing, and the influence which has displacement to be more remarkable, Because had considered the mutual support of the pillar both sides node rigidity in different time, the column's effective length factor has reduces, and the reduced extent is big in the situation of displacement. The bigger of the pillar both sides semi-rigid node rigidity differential value, the bigger of effective length factor reduces the scope to be. Therefore, suggests when the computation semi-rigid connected frame, especially when the pillar both sides semi-rigid node rigidity differential value is big, should carry on the computation according to the formula which this article proposed to, this will obtain more precise solution than compared to a sub-structure law.